Fix in key frame detection
Fix in key frame detection

The frame next to scene cut frame does not usually have
a high second ref useage. Thus the sec ref useage of the
frame next to scene cut frame is tested against a
threshold for scene cut detection.

With this change scene cut detection is improved for
contents where genuine scene cuts were being missed.

Change-Id: I11190d848fa1c1dcd63aab81da799354371e2a30

webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx